Answer
To make yogurt at home try this method.
Ingredients
Milk - 500 ml
Curd/ Plain Yogurt from previous batch as a starter - 2 tsp
Method
1. Boil milk in a pan and switch off. Leave it to cool. Let it become lukewarm.
2. When it is lukewarm, (just dip you little finger to check the temperature) add 2 tsp of curd and mix well. Alternatively you can pour milk for one container to another 2-3 times so that the curd mixes well with the milk. Then transfer the milk into a container with lid. Keep a separate container for making curd. You can also set curd in individual cups as shown in the picture above.
3. Leave the container undisturbed in a warm place for 5-6 hours. The curd will set within 5-6 hours under favorable conditions.
Refrigerate once the curd sets. It becomes firm after 2-3 hours of refrigeration. If you leave the curd outside for a long time, it will become sour."